The present invention relates to a method and its system for calibrating measured data between different measuring tools capable of performing a highly accurate calibration between different measuring tools by sampling in consideration of local dispersion in sample dimension such as line width roughness
As a measuring instrument with a resolution of nanometer order, there has been known a Critical-Dimension Scanning Electron Microscopy (CD-SEM) tool. The CD-SEM tool is stable and has a high throughput. However, since it measures the dimensions of a pattern (CD) by using only top-down view of SEM image, it has a problem in that it is unclear where in the height direction of a pattern, that is, where in the cross section of an upper, a lower or a middle portion therebetween the CD-SEM tool measures.
On the other hand, as a measuring instrument capable of measuring cross section dimension, cross-section observation using a scanning transmission electronic microscope (STEM) tool, a transmission electronic microscope (TEM) tool, and a cross-section observation SEM tool, as well as cross-section observation using an atomic force microscope (AFM) tool have been known. The configuration of the STEM tool is described in, for example, JP-A 2003-287508. The configuration of the AFM tool is described in, for example, JP-A 2006-118867. The STEM tool, the cross-section observation SEM tool, the AFM tool and the TEM tool have the advantages that they can relatively accurately measure cross section dimension. The AFM tool, however, has a problem in that it requires a longer measuring time than the CD-SEM tool. For the STEM tool, the cross-section observation SEM tool and the TEM tool, require sample preparation such as FIB process for cross-sectional imaging/measurements, causing a problem in that a measuring cost becomes higher than that of the AFM tool.
A calibration method in which each dispersion of measurement of different measuring tools is taken in consideration is disclosed in JP-T 2006-510912.
The above CD-SEM tool is capable of measuring the dimensions at multiple positions, which are observed by a top-down SEM image. taking into account the pattern size variation in a high throughput. However, On the other hand, the STEM tool, the cross-section observation SEM tool, the AFM tool or and the TEM tool can relatively accurately measure the cross section shape (three-dimensional shape) of a measurement pattern than the CD-SEM tool, so that they can perform calibration with the dimension at a desired height, however, it is hard for them to measure too many points.
For this reason, at the time of calibration between the CD-SEM tool and the cross-section observation SEM tool or the AFM tool, there is a problem in that it is not clear that the measurement result of cross section shape measured with limited sampling capability with the STEM tool, the cross-section observation SEM tool, the AFM tool or and the TEM tool corresponds to which of the dimension measured with the CD-SEM.